FIX: do not block registration for whitelisted IP address

lib/spam_handler.rb

@@ -16,6 +16,9 @@ class SpamHandler
 
     return false if staff_members_with_same_ip > 0
 
+    ip_whitelisted = ScreenedIpAddress.is_whitelisted?(ip_address)
+    return false if ip_whitelisted
+
     tl0_accounts_with_same_ip = User.unscoped
                                     .where(trust_level: TrustLevel[0])
                                     .where(ip_address: ip_address.to_s)